Question

Kinetic energy or energy in motion depends on the mass and the motion of an object. In formula, KE = 1/2mv^2. An object with 8 m/s has a kinetic energy of 168 joules. how much kinetic energy would it have if its speed were reduced to 2m/s?

a) 10.5 J
b) 21 J
c) 42 J
d) 63 J

Answer 1

Kinetic energy or energy in motion depends on the mass and the motion of an object. In formula, $KE = 1/2mv^2$. An object with $8 \, \text{m/s}$ has a kinetic energy of 168 joules. how much kinetic energy would it have if its speed were reduced to $2 \, \text{m/s}$?

a) 10.5 J

b) 21 J

c) 42 J

d) 63 J

Please explain

Answer:

Such as the kinetic energy is: $E_{k} = \frac{1}{2} mv^{2}$, the kinetic energy proportional to a square of velocity. If velocity were reduced from $8 \, \text{m/s}$ to $2 \, \text{m/s}$: $\frac{8}{2} = 4$, the kinetic energy will be: $\frac{168}{4^{2}} = \frac{168}{16} = 10.5 \, \text{J}$

Answer: "a"